This invention relates generally to nano-circuits. More particularly, the invention relates to vertically oriented nano-fuses and nano-resistors in manufacturing semiconductor devices.
The demand for semiconductor devices has increased dramatically in recent years. One can readily observe the pervasiveness of consumer electronic devices in the modern world. Most or all of the consumer electronic devices are made possible because of developments in the semiconductor devices. As the electronic devices become smaller, more sophisticated, and less expensive, increasingly higher densities of the semiconductor devices are demanded at a lower cost in today""s market place. This requires that the circuits within the device be more dense as well.
One of the basic circuit elements may be a fuse or a resistor, which may be electrically connected to conductors. The electrical connection may be maintained with an addition of a diode or other circuit elements in series with the fuse and/or the resistor.
In some semiconductor devices, thin film fuses and resistors are lithographically patterned in the plane of the semiconductor substrate to create a circuit element. Circuits made of such elements are adequate for low density application. Unfortunately, in order to integrate a planar fuse or resistor into a circuit requires a minimum area of 8xcex2 (where xcex is the minimum photolithographic feature size), since a contact region is needed on each end of the fuse. Generally the fuse occupies space even larger than 8xcex2. As such, their use in high density applications is limited due to a consumption of a significant amount of silicon (xe2x80x9cSixe2x80x9d) real estate. Thus, thin film fuses and/or resistors typically are not used in application where density is critical.
In one respect, an exemplary embodiment of a vertically oriented nano-circuit may include a top conductor extending in a first direction and a bottom conductor extending in a second direction. The top and bottom conductors may define an overlap, and the two conductors may be electrically connected. The vertically oriented nano-circuit may also include a vertically oriented conductive spacer formed between the top and bottom conductors in the overlap region. The conductive spacer may be electrically connected with both top and bottom conductors. The conductive spacer may be a vertically oriented nano-fuse or a vertically oriented nano-resistor. A second circuit element, perhaps vertically oriented as well, may be connected in series with the vertically oriented conductive spacer.
In another respect, an exemplary embodiment of a method to form a vertically oriented nano-circuit may include forming a top conductor extending in a first direction and forming a bottom conductor extending in a second direction. Again, the top and bottom conductors may define an overlap. The method may also include forming a vertically oriented conductive spacer in the overlap and such that top and bottom conductors are electrically connected.
The above disclosed exemplary embodiments may be capable of achieving certain aspects. For example, a thin film conductive element, either a fuse or a resistor, when oriented perpendicular to the substrate plane, is ideally suited to be placed between adjacent metallization levels, which allows for a dramatically increased density. The element may be inserted between tow metallization levels without the need for additional area beyond the area of overlap of the two metallization levels. Also, the fuse or the resistor may be easily combined in series with an anti-fuse or a diode with no loss in density. In addition, the devices can be made with well-known semiconductor processes, such as the Damascene process. Thus, little to no capital investment may be required beyond the currently existing equipment.